Many pieces of furniture and appliances are supported by legs. If the legs are of unequal length or the supporting surface is uneven an instability occurs which manifests itself as tipping or wobbling under perturbations to the article of furniture, jarring forces and the like. Stabilizing devices may also be used to help level an otherwise evenly supported article on a support surface.
For example, a typical table has a horizontal dining surface oriented parallel to the floor and supported by four downwardly depending legs. Thus, the support plane of this table is the plane defined by the free ends of the legs. However, geometry dictates that only three support points define a plane. Thus, it is necessary that table legs be sized with great care in order to ensure that all four free ends terminate in a common plane; otherwise, the table will be unstable.
Most articles of furniture are usually supported by lower support members which indeed have a number of potential support points in excess of three. These include, by way of example, articles of furniture, such as the table, above, which have four or more downwardly depending legs, articles which have horizontal runners adapted to abut the support surface and pedestal supported articles. Unless care is taken, it is possible that the lower support structure of these articles does not terminate in a common support plane. When this happens, the article of furniture does not have a single stable support plane but rather is subject to unwanted wobbling or tipping. Even with articles of furniture which have only three support points, such as a three legged table, automatically defining a stable support plane, the working surface may be tilted due to an error in the length of any support.
Given the foregoing, there have been a number of inventions made to level or otherwise stabilize. Some articles of furniture are provided with adjustable pads on their lower supports such pads typically being threaded bolts which terminate in support pads or heads. These threaded bolts move into and out of the lower supports to define an adjustable support plane. Other techniques of levelling items such as heavy machinery include the use of a pair of freely sliding wedges interconnected by means of a threaded shaft such as illustrated in the patents of King and Mafera (U.S. Pat. Nos. 1,045,984 and 2,709,571 respectively).
A number of approaches to furniture leg stabilizers use the wedge concept. However, there are a number of drawbacks. U.S. Pat. No. 4,830,320 by Robert K. Bellows, incorporated herein by reference, and the patents of Costar (U.S. Pat. No. 3,030,730), Bogle (U.S. Pat. No. 4,625,489), and Jensen (U.S. Pat. No. 4,135,335) all suggest using a combination of wedges having ridges which intermesh with each other for stability. This however does not provide for small adjustments typically needed (as small as 1 millimeter) and for larger adjustments (up to 15 millimeters) stability is compromised.
While Bellows incorporates ridges and semi-flexible material to decrease the likelihood that the wedge will slip out from under the table leg, it is still vulnerable to side thrusts. Further, one needs two separate wedges to provide a large height adjustment. From the background it can be seen that there is a need for a device that provides greater adjustment height without having two separate pieces and without having a chance for coming apart when the table is bumped.